Electrode mounting for high-power electron discharge devices



Dec. 19, 1950 FIG. lg 38 V. L. RONCI ELECTRODE MOUNTING FOR HIGH-POWERELECTRON DISCHARGE DEVICES 12 32 l I so I! 1 22 32 /0 FIG? a 40 41 \Y. I40 INVENTOR l. LJPONCI A TIURNEV Dec. 19, 1950 v. L. RONCI ELECTRODEMOUNTING FOR HIGH-POWER nmcmon DISCHARGE mzvxcms 2 Sheets-Sheet .2

Filed March 5, 1949 Fla4 ATTORNEY Patented Dec. 19, 1950 ELECTRODEMOUNTING FOR HIGH-POWER.

ELECTRON DISCHARGE DEVICES Victor L. Ronci, Zionsville, Pa., assignortoBell Telephone Laboratories, Incorporated, New

York, N. Y., a. corporation of New York I Application March 5, 1949,Serial No."79',756.

8 Claims.

This invention relates to electron discharge devices and moreparticularly to electrode assemblies for such devices of high powercapacity.

An object of this invention is to prevent the setting up of deleteriousstresses in a glass to metal seal which supports an electrode assembly.

In one embodiment of this invention, a filamentary cathode structure ofthe type disclosed in Patent 1,976,521 to V. L. Ronci and J. E. Clark.issued October 9, 1934, is modified in its method of connection to oneof the vitreous end portions of the device, thereby eliminating theadverse strains set up between said end portion and the metallic-base ofsaid electrode structure.

This cathode assembly includes a metallic collar which is sealed to areentrant stem in one end of the envelope and is formed with a pluralityof tabs cut in its surface and extending parallel to its axis. Each tabis connected to one or more elements of the cathode support. These tabsare secured to the flanges of a spool which is thereby maintained withinthe collar to serve as a support for a guide through which extends acentral cathode support rod, Exterior of the colla and secured theretothrough connection to the tabs is a band or sleeve which supports theupper periphery of a frusto-conical wire mesh shield, The lowerperiphery of this shield is connectedto a filament platform whichmaintains its spacing from the enclosed conductor rods, insures theposition of those rods relative to each other, and also connects theshield elements to the major filament support structure.

In assembling structures of this type, it has been found that the collarafter fusion to the vitreous end, often assumes a form other than thatof a true right circular cylinder. When the spool supporting the cathodestructure is mounted in a collar of the form disclosed in theaforementioned patent, the alteration of its cross section, when thecross section ha assumed a form other than a right circular cylinder, toa true circle, occasioned by the securing of the circular spool flangesby direct connection to the collar body, causes strains in theglass-to-metal seal between the stem and the collar which result infractures and thus the destruction of the semiprocessed tube element.Further, while tubes of this type are normally operatedwith their axesvertical, it is not possible to insure that they will be maintained soduring shipping, hence gravitational forces and the jars incident toshipment tend to cause movement of the elements transverse to the tubeaxis. These forces, due to the length of the electrodes of this type oftube, exert a large moment about the base of the electrode structure,and therefore strains, often of destructive force on the glass-to-metalseal at the collar.

It will be noted that the structure as briefly disclosed above, issecured to the collar solely by flexible couplings, comprising theaforementioned axial tabs. The flexibilityof these tabs-permits a tightconnection to the spool without pulling the entire surface of the collarinto the form of a true right circular cylinder, thereby eliminating thestrain developed in the seal by such a change in form. The strainswhich. occur in shipping arealso minimized to a large extent by theflexibility of the connection between the collar base and the otherportions of the filament-structure through the tabs to the supportingband of the wire mesh shield and the spool in the collar. Thus failuresat the seal between the base collar and the glass stem of the envelopein structures of this type have been materially reduced by the expedientof employing these tabs to provide flexible couplingsbetween theelectrode structure and the seal.

The invention and the features thereof will be understood more clearlyand fully from the following detailed description, reference being-hadto the accompanying drawings in which:

Fig. 1 is an elevational view of the cathode assembly of a deviceillustrative of one embodiment of the invention;

Fig. 2 is an enlarged elevational view, partially cut away, of theportion of the cathode support assembly including the seal between theglass stem and the metal collar and the associated elements within thecollar, the shield and its supporting element being omitted for purposesof clarity;

Fig. 3 is an enlarged view in perspective of the glass stem and themetallic collar, showing in detail the flexible support tabs of thecollar;

Fig; 4 is an exploded view of the filamentary cathode assembly of Fig.1, partially broken away to show the conductor rod assemblymore clearly.

Referring now to the drawings, an electrode structure illustrative ofone embodiment of this invention, comprises a metallic sleeve or collarI0 which is sealed at its upper periphery l l to a hollow reentrancestem [2 of one end of the tube envelope (not shown) to serve as the basefor a filamentary cathode structure. This collar I0 is provided with aplurality of tabs l3 and 14, as best illustrated in Fig. 3, which areapertured to provide passages for screws which secure the remainder ofthe cathode structure, Within the collar and secured thereto by screwsl5 pass- 3 ing through the tab apertures I6 is a spool I! havin endflanges [8 which are interconnected by a spindle or tubular portion l9and which have tapped holes in their periphery registering with theholes [6 in the collar tabs l3 and M. This spool ll rigidly supports acentral tubular guide member 2| in which is slidably mounted a cathodesupport rod or standard 22 extendin from the lower end of the guide 2|axially of the envelope within the length of the anode (not E shown) andprojecting from the upper end of the guide tube 2|. A plate 23 ispositioned adjacent the upper spool flange [8 but out of contacttherewith and is supported solely by machine screws 24 which arethreaded into tapped holes 3 in it, and which slidably extend throughapertures in the spool flanges l8. The screws 24 may be locked relativeto each other by a cotter wire 21. A helical tension spring 28 encirclesthe standard or rod 22, one of its ends 29, being secured to the plate23, while the other end 39 is secured to a cap 3| on the end of the rod22 thereby exerting a downward force on said rod.

Lead-in conductor rods 32 extend through glass seals (not shown),through the reentrant stem 52, and apertures 33 in the spool flanges l8so that no contact is made with the eiements within the collar. Thelower ends of these rods 32 are enlarged and have a bore 34 into which areduced end 35 of a more refractory section 3% of conductor rod extends.Ihese sections are preferably weldedv together, in one embodimentcomprising copper lead-in sections and molybdenum end sections a nickelwelding sleeve 3'1 is interposed between the section ends. Each of thelower rod sections 36 is formed with a threaded portion (not apparentfrom the drawings) and an elongated linear portion 38 extending axial ofthe envelope and within the anode of the device (not shown). Portions ofthese elongated sections extend through opposed flanged insulators 48,positioned in apertures in a metallic platform 42, and each portion hasmounted thereon a nut 43, which clamps the insulators 48 againstshoulders 44 on rods 36, and thereby secures the platform in position. Aplurality of rods 25 extending through flanged insulators 46 in platform42 and have secured thereto, as by welding or some other convenientmethod, metallic buttons ll which lock the insulators in position. Therods 45, which may be of molybdenum, are provided with end portions 48which are secured to the rod sections 36 as shown so that threeconductors of positive polarity and three conductors of negativepolarity are provided below the filament platform, each group of threecomprising one conductor rod 38 and two conductor rods 45. The rods 55and 38, the rods 36 and 32, and the platform 42 in the specificconstruction shown, are therefore rigidly interconnected and form aunitary assembly supported from the stem 12 through the screws l5 whichconnect the supports for these elements to the tabs l3. Thus aconnection is formed which under operating conditions, i. e. when thetube is mounted so that the filament support structure is vertical,provides a coupling of sufficient rigidity and strength to maintain theproper position of the filamentary cathode relative to the otherelectrodes, however,

when the device is so positioned that the gravitational forces on thefilament structure are transverse to the axis or it is so handled thattransverse forces are applied to the structure, the tabs, by virtue oftheir flexibility, will permit a limited transverse movement of thestructure,

4 thereby taking up the strain which would be applied to theglass-to-metal seal if the elements of the structure were supporteddirectly upon the body of the collar.

The platform 42 is slidably mounted on the guide member 2! so that whileit supports and acts as a spacer for the rods 38 and by being rigidlyconnected thereto, it does not cause those elements to buckle when theyexpand and contract during the thermal changes in the tube. A spacerdisc 49 is located below the platform 42 further insuring uniformspacing of the ends 58 of the rods 38 and 45. The rods of negativepolarity are secured directly to the disc 49 thereby fixing itspotential, while the rods of positive polarity pass through insulatingbushings 5!.

The ends 50 of the rods 38 and 45 have central bores adapted to receivethe ends of filament lengths 53 which are welded therein through slots52 extending into the bores. A disc 54, which may be of molybdenum, ismounted upon a reduced headed extension of the standard 22, and isuniversally rockable with respect to the standard 22.

A filamentary cathode consisting of a plurality of lengths 53 formingV-shaped sections, which may be of tungsten, is suspended between theends 50 of the rods 38 and as and the platform 54, and is arranged witha substantially cy1indrical boundary concentrically within the otherelectrodes of the device (not shown). The V-shaped sections of thecathode are threaded through bores in the platform 54 and the ends ofthe sections are disposed in the bores of conductor rods 38 and 45 asdescribed above. This connection arrangement, as most clearly shown inFig. 4, places the sections of the cathode electrically in parallel.

The normal position of the cathode structure is as shown in Fig. 1. Thestandard 22 which is freely slidable in the guide member 2| constitutesa gravity actuated mass member the mass of which acts along the lengthof the cathode and thereby produces a tension in the filamentary lengths53 of the cathode. The degree of the tension may be adjusted by varyingthe separation of the plate 23 and the disc l8 through the medium of themachine screws 24, thereby varying the tension on the helical spring 28.During the operation of the device, the expansion and contraction of theleading-in conductor rods 32 and 35 is accompanied by movement of theplatform 42 along the guide 2|, so that no buckling or deleteriousstresses are produced in the rods. The expansion and contraction of thefilamentary sections 53 of the cathode are compensated by the helicalspring 28 acting upon the standard 22. An unequal expansion of thesections 53 is compensated by the rocking movement of the platform 54.This construction therefore maintains substantially uniform and constanttension in the section 53 and preserves the form of the cathode as awhole so that the spacing of the cathode with respect to the anode issubstantiaily uniform and the electrical characteristics of the deviceare maintained substantially constant.

In order to prevent arcin discharges between the anode and relativelysharp edges of portions of the cathode supporting structure and toeliminate the electronic bombardment on the glass of the reentrant stem,a shield is provided above the assembly adjacent the stem l2. Thisshield comprises a cylindrical supporting band 5t which is secured tothe sleeve or collar II] by screws 57 which pass through tapped holes inthe tabs M on the collar and into registering holes in the periphery ofthe spool flanges i8 and frusto-conical perforated or wire mesh portion58 extends from the lower periphery of the band 56 to the periphery ofplatform 42 and makes sliding contact with the platform. By thisarrangement the shield and its associated elements are also connected tothe sleeve or collar IE3, solely through the medium of the flexible tabs13 and I4 and hence any strain placed upon the shield by these memberswill be taken up by the tabs, thereby relieving the glass-to-metal sealat the collar periphery ll.

What is claimed is:

1. An electrode assembly mounting comprising a glass portion, a metalliccollar sealed thereto, a plurality of flexible portions cut in thesurface of said collar, and a rigid electrode portion extending beyondsaid glass portion and supported from said flexible collar portions.

. 2. An electrode assembly mountin comprising a glass portion, ametallic collar sealed thereto, a plurality of flexible portions in thesurface of said collar and parallel to the axis thereof, and a rigidelectrode portion extending beyond said glass portion and supported fromsaid flexible collar portions.

3. An electrode assembly mounting comprising a glass portion, a metalliccollar sealed thereto, a plurality of flexible portions cut in the wallof said collar and parallel to the axis thereof, a support mounted onsaid flexible collar portions, a standard extending through said supportand slidable therein, a filamentary electrode having portions connectedto said support and other portions supporting said standard, and anadjustable resilient connection joining said standard and said support.

4. An electrode assembly mounting comprising a glass portion, a metalliccollar sealed thereto, aplurality of flexible portions in the surface ofsaid collar and parallel to the axis thereof, a spool fitting withinsaid collar and mounted on said flexible collar portions, a tubularguide member secured within the spindle of said spool, a standardslidably mounted within said guide member, an adjustable resilientconnection joining said standard and said spool, and a filamentaryelectrode having portions connected to said spool and other portionssupporting said standard.

5. An electrode assembly mounting comprising a glass stem, a metalliccollar sealed thereto, a plurality of flexible portions in the surfaceof the collar and parallel to the axis thereof, a support mounted onsaid flexible collar portion, a standard extending from the support,leading-in conductors extending through said stem, a platform supportedby said conductors loosely surrounding the standard, a second platformmounted on said standard and universally rockable with respect thereto,and a filamentary cathode coupled to and extending between the ends ofsaid leading-in conductors and said second platform.

6. An electrode assembly mounting comprising a glass stem, a metalliccollar sealed thereto, a plurality of flexible portions in the surfaceof said collar and parallel to the axis thereof, an electrode extendingbeyond said lass stem and supported from said flexible collar portions,and a hollow shield encircling said collar, said shield being secured tosaid flexible portions of said collar.

7. An electrode assembly mounting comprising a glass stem, a metalliccollar sealed thereto, a plurality of flexible portions in the surfaceof said collar and parallel to the axis thereof, a support mounted onsaid flexible portions of said collar, a standard extending from saidsupport, leadingin conductors adjacent said standard and extendingthrough said stem, a platform slidably encircling said standard andcarried by said conductors, a second platform mounted on said standard,a filamentar electrode supported between said second platform and theends of said leading-in conductors, and a hollow shield encircling saidcollar, a portion of said standard, and a portion of said leading-inconductors, said shield being secured to said flexible portions of saidcollar at one end and slidably connecting with said first platform atits other end.

8. An electrode assembly mounting comprising a glass portion, a metalliccollar sealed thereto, an electrode extending beyond said glass portion,a tubular shield attached to said electrode and surrounding said collar,said collar having flexible portions parallel to said shield, andconnections fastening said shield to said flexible portions.

VICTOR L. RONCI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,882,936 Ronci Oct. 18, 19322,113,671 Zottu Apr. 12, 1938 2,164,477 Smith July 4, 1939 2,385,435Werner et a1 Sept. 25, 1945 2,441,349 Eitel May 11, 1948 2,458,218Skehan Jan. 4, 1949 2,489,872 Elder et al Nov. 29, 1949

